In order to improve the set retention of a hair cosmetic composition, the content of a set polymer or an oil component is generally increased. If the content of a set polymer is simply increased, however, the setting the hairstyle with the hair cosmetic composition may become hard and stiff. Besides, when a hair cosmetic composition containing a set polymer is used, if the hairstyle set with the hair cosmetic composition once becomes disheveled, the hair generally cannot be restyled. On the other hand, when a hair cosmetic composition containing an oil component is used, the hair can be restyled after the hairstyle is disheveled; however the set retention is much weaker than that obtained by using a set polymer. If the content of the oil component is increased for improving the set retention, the hair set with such a hair cosmetic composition becomes sticky.
Therefore, a hair cosmetic composition using a specific set polymer for enabling hair restyling has been proposed (for example, Patent Document 1). Using such a set polymer enabling hair restyling causes, however, stickiness if sufficient set retention is provided, and on the other hand, if a less sticky polymer is used, sufficient set retention cannot be obtained. Thus, it is difficult to simultaneously obtain both performances.
An oxyalkylene polymer (polyalkylene glycol) has been used in a hair cosmetic composition for, for example, improving solubility, adjusting viscosity of a formulation, controlling feel, and providing plasticity. A hair cosmetic composition using such an oxyalkylene polymer, for example, using solid polyalkylene glycol and liquid polyalkylene glycol, and further using a film-forming polymer, for providing restyling performance and improving hair setting performance, is known (Patent Document 2).
Furthermore, an oxyalkylene polymer has also been used as a plasticizer for improving brittleness of a film-forming polymer used in a hair cosmetic composition. For example, a technique to obtain a hair cosmetic composition excellent in both hair setting performance and restyling performance by adding, to a specific hair set polymer, polyalkylene glycol in a substantially equivalent amount for providing adhesiveness is known (see Patent Document 3). Among these film-forming polymers, acidic polymers having, for example, a carboxy group in their structures are mostly available as neutralized products. Even when raw material is prepared or purchased as an acidic (not neutralized) type material, it is generally neutralized upon addition to a composition at about a neutral condition for securing its solubility and for easy cleaning properties of the dried film, and such an acidic type raw material is not used under acidic conditions.
On the other hand, in order to reduce the stickiness of a hair cosmetic composition containing a set polymer, the hair cosmetic composition has been conventionally improved by adding an oil component or a nonvolatile solvent for improving lubrication properties. When such a component is added, however, the ability to set the hair or the ability to restyling the hair may be hindered. As a countermeasure, there is a technique for withdrawing the stickiness of a hair cosmetic composition as well as to improve the hair set performance and the restyling performance, which have not been simultaneously obtained in the conventional techniques (see Patent Document 4). According to this technique, a polymer has adhesive properties characterized in that adhesion of the polymers itself (hereinafter referred to as the “self-adhesive force”) is strong; on the other hand, adhesion to the other materials (hereinafter referred to as the “other-adhesive force”) is weak (wherein the polymer having both properties of self-adhesive force and other-adhesive force will be hereinafter referred to as the “self-selective adhesiveness”). Such polymer having such self-selective adhesiveness is contained in the hair cosmetic composition of Patent Document 4, in order to obtain sufficient hair setting ability and ability to restyling the hair, and to reduce stickiness and stiffness of the hair. However, since the structure of a composition described in Patent Document 4 includes a carbonate bond, solvolysis is caused by water or ethanol, and therefore, long-term storage stability cannot be secured in a formulation system containing such a composition.